Lane departure prevention apparatus

ABSTRACT

A lane departure prevention apparatus ( 17 ) has: a departure preventing device ( 172 ) for preventing a vehicle ( 1 ) from departing from a driving lane by controlling at least one of a steering apparatus ( 142 ) and a braking apparatus ( 13 ) selected on the basis of a state of the vehicle, when it is determined that the vehicle may depart from the driving lane; and a determining device for determining whether or not an abnormality condition that it is difficult for a person to normally drive the vehicle is satisfied, the departure preventing device prevents the vehicle from departing from the driving lane by controlling the braking apparatus even if the state of the vehicle is not a predetermined state in which the departure preventing device should prevent the vehicle from departing from the driving lane by controlling the braking apparatus, when it is determined that the abnormality condition is satisfied.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.15/864,110 filed Jan. 8, 2018 (allowed), which claims priority fromJapanese Patent Application No. 2017-026725 filed Feb. 16, 2017. Theentire disclosures of the prior applications are considered part of thedisclosure of the accompanying continuation application, and are herebyincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a technical field of a lane departureprevention apparatus that is configured to prevent a vehicle fromdeparting from a driving lane on which the vehicle is currentlytraveling.

BACKGROUND ART

One example of a lane departure prevention apparatus is disclosed in aPatent Literature 1. Specifically, the Patent Literature 1 discloses thelane departure prevention apparatus that is configured to prevent avehicle from departing from a driving lane by activating a LKA (LaneKeep Assist) until it is determined that an abnormality of a person (forexample, a driver) in the vehicle continues to be detected and thus theperson is in a driving-impossible-state (namely, the person cannot drivethe vehicle) after the abnormality of the person is detected, whereinthe LKA is an operation for allowing the vehicle to travel (namely, moveor run) along the driving lane.

CITATION LIST Patent Literature

[Patent Literature 1] Japanese Unexamined Patent Application PublicationNo. 2016-196285

SUMMARY OF INVENTION Technical Problem

The lane departure prevention apparatus disclosed in the PatentLiterature 1 prevents the vehicle from departing from the driving laneby applying, to a handle (namely, a steering wheel), a steering forcethat is allowed to prevent the vehicle from approaching a zoning line(for example, a white line) that zones the driving lane. However, whenit is difficult for the person to drive the vehicle, there is apossibility that the person loses consciousness and falls onto or leansagainst the handle. In this case, there is a possibility that the handleis substantially immovable (in other words, fixed) by the unconsciousperson. As a result, even if the steering force for preventing thevehicle from departing from the driving lane is applied to the handle,there is a possibility that the steering force applied to the handlecannot turn turned wheels that is coupled to the handle. Thus, there isa possibility that the lane departure prevention apparatus disclosed inthe Patent Literature 1 cannot prevent the vehicle from departing fromthe driving lane in the situation where it is difficult for the personto normally drive the vehicle.

The above described technical problem is one example of the technicalproblem that is to be solved by the present invention. It is thereforean object of the present invention to provide, for example, a lanedeparture prevention apparatus that is configured to appropriatelyprevent the vehicle from departing from the driving lane even in thesituation where it is difficult for the person in the vehicle tonormally drive the vehicle.

Solution to Problem

<1>

One aspect of a lane departure prevention apparatus has a controller,the controller is programmed to: determine whether or not a departurecondition is satisfied, the departure condition being a condition thatthere is a possibility that a vehicle departs from a driving lane onwhich the vehicle is currently traveling; prevent the vehicle fromdeparting from the driving lane by controlling at least one of asteering apparatus and a braking apparatus of the vehicle that isselected on the basis of a traveling state of the vehicle, when it isdetermined that the departure condition is satisfied; and determinewhether or not a predetermined abnormality condition is satisfied, theabnormality condition is a condition that it is difficult for a personin the vehicle to normally drive the vehicle, the controller isprogrammed to prevent the vehicle from departing from the driving laneby controlling at least the braking apparatus even if the travelingstate of the vehicle is not a predetermined state in which thecontroller should prevent the vehicle from departing from the drivinglane by controlling the braking apparatus, when it is determined thatthe departure condition and the abnormality condition are satisfied.

Alternatively, one aspect of a lane departure prevention apparatus mayhave: a first determining device that is configured to determine whetheror not a departure condition is satisfied, the departure condition beinga condition that there is a possibility that a vehicle departs from adriving lane on which the vehicle is currently traveling; a departurepreventing device that is configured to prevent the vehicle fromdeparting from the driving lane by controlling at least one of asteering apparatus and a braking apparatus of the vehicle that isselected on the basis of a traveling state of the vehicle, when it isdetermined that the departure condition is satisfied; and a seconddetermining device that is configured to determine whether or not apredetermined abnormality condition is satisfied, the abnormalitycondition is a condition that it is difficult for a person in thevehicle to normally drive the vehicle, the departure preventing deviceis configured to prevent the vehicle from departing from the drivinglane by controlling at least the braking apparatus even if the travelingstate of the vehicle is not a predetermined state in which the departurepreventing device should prevent the vehicle from departing from thedriving lane by controlling the braking apparatus, when it is determinedthat the departure condition and the abnormality condition aresatisfied.

According to one aspect of the lane departure prevention apparatus, thedeparture of the vehicle from the driving lane is prevented bycontrolling the braking apparatus to apply braking force to the vehicle,when it is determined that the abnormality condition is satisfied. Thus,the departure of the vehicle from the driving lane is appropriatelyprevented, even if the person loses the consciousness and falls onto orleans against a handle of the vehicle and thus it is determined that theabnormality condition is satisfied. Namely, the lane departureprevention apparatus is capable of appropriately prevent the vehiclefrom departing from the driving lane in the situation where it isdifficult for the person in the vehicle to normally drive the vehicle.

<2>

In another aspect of the above described lane departure preventionapparatus, the controller is programmed to prevent the vehicle fromdeparting from the driving lane by controlling at least the brakingapparatus, when it is determined that the departure condition and theabnormality condition are satisfied, the controller is programmed toprevent the vehicle from departing from the driving lane by controllingat least one of the braking apparatus and the steering apparatus, whenit is determined that the departure condition is satisfied and theabnormality condition is not satisfied.

Alternatively, in another aspect of the above described lane departureprevention apparatus that has the departure preventing device, thedeparture preventing device is configured to prevent the vehicle fromdeparting from the driving lane by controlling at least the brakingapparatus, when it is determined that the departure condition and theabnormality condition are satisfied, the departure preventing device isconfigured to prevent the vehicle from departing from the driving laneby controlling at least one of the braking apparatus and the steeringapparatus, when it is determined that the departure condition issatisfied and the abnormality condition is not satisfied.

According to this aspect, the departure of the vehicle from the drivinglane is prevented by controlling at least one of the steering apparatusand the braking apparatus that is selected on the basis of the travelingstate of the vehicle as a usual case, when it is determined that theabnormality condition is not satisfied. On the other hand, the departureof the vehicle from the driving lane is prevented by controlling thebraking apparatus as an exceptional case, when it is determined that theabnormality condition is satisfied. Thus, the lane departure preventionapparatus is capable of appropriately prevent the vehicle from departingfrom the driving lane in the situation where the person in the vehiclehas any abnormality.

Note that the controller may be programmed to prevent the vehicle fromdeparting from the driving lane by controlling at least the brakingapparatus, when it is determined that the departure condition issatisfied and the abnormality condition is not satisfied and thetraveling state of the vehicle is the predetermined condition, thecontroller may be programmed to prevent the vehicle from departing fromthe driving lane by controlling at least the steering apparatus, when itis determined that the departure condition is satisfied and theabnormality condition is not satisfied and the traveling state of thevehicle is another condition in which the controller should prevent thevehicle from departing from the driving lane by controlling the steeringapparatus, and the controller may be programmed to prevent the vehiclefrom departing from the driving lane by controlling at least the brakingapparatus, when it is determined that the departure condition and theabnormality condition is satisfied, regardless of the traveling state ofthe vehicle being the predetermined condition or the another condition.Alternatively, the departure preventing device may be configured toprevent the vehicle from departing from the driving lane by controllingat least the braking apparatus, when it is determined that the departurecondition is satisfied and the abnormality condition is not satisfiedand the traveling state of the vehicle is the predetermined condition,the departure preventing device may be configured to prevent the vehiclefrom departing from the driving lane by controlling at least thesteering apparatus, when it is determined that the departure conditionis satisfied and the abnormality condition is not satisfied and thetraveling state of the vehicle is another condition in which thecontroller should prevent the vehicle from departing from the drivinglane by controlling the steering apparatus, and the departure preventingdevice may be configured to prevent the vehicle from departing from thedriving lane by controlling at least the braking apparatus, when it isdetermined that the departure condition and the abnormality condition issatisfied, regardless of the traveling state of the vehicle being thepredetermined condition or the another condition.

<3>

In another aspect of the above described lane departure preventionapparatus, an operation state of the controller is changed between an ONstate in which the controller is allowed to control at least one of thesteering apparatus and the braking apparatus and an OFF state in whichthe controller does not control both of the steering apparatus and thebraking apparatus, the controller is programmed to change the operationstate to the ON state and then to prevent the vehicle from departingfrom the driving lane by controlling at least the braking apparatus,when it is determined that the departure condition and the abnormalitycondition are satisfied and the operation state is the OFF state.

Alternatively, in another aspect of the above described lane departureprevention apparatus that has the departure preventing device, anoperation state of the departure preventing device is changed between anON state in which the departure preventing device is allowed to controlat least one of the steering apparatus and the braking apparatus and anOFF state in which the departure preventing device does not control bothof the steering apparatus and the braking apparatus, the departurepreventing device is configured to change the operation state to the ONstate and then to prevent the vehicle from departing from the drivinglane by controlling at least the braking apparatus, when it isdetermined that the departure condition and the abnormality conditionare satisfied and the operation state is the OFF state.

According to this aspect, even if the operational state of thecontroller or the departure preventing device is the OFF state at thetiming when it is determined that the abnormality condition issatisfied, the operational state of the controller or the departurepreventing device is changed to the ON state after it is determined thatthe abnormality condition is satisfied. Thus, the departure of thevehicle from the driving lane is prevented by using the brakingapparatus. Therefore, it is possible to increase an opportunity that thedeparture of the vehicle from the driving lane is prevented. Thus, thelane departure prevention apparatus is capable of appropriately preventthe vehicle from departing from the driving lane in the situation wherethe person in the vehicle has any abnormality.

<4>

In another aspect of the above described lane departure preventionapparatus, the controller is further programmed to control the steeringapparatus so that the vehicle travels within the driving lane,regardless of the possibility that the vehicle departs from the drivinglane, the controller is programmed to prevent the vehicle from departingfrom the driving lane by controlling the steering apparatus and thebraking apparatus, when it is determined that the departure conditionand the abnormality condition are satisfied and the controller controlsthe steering apparatus so that the vehicle travels within the drivinglane, the controller is programmed to prevent the vehicle from departingfrom the driving lane by controlling the braking apparatus, when it isdetermined that the departure condition and the abnormality conditionare satisfied and the controller does not control the steering apparatusso that the vehicle travels within the driving lane.

Alternatively, in another aspect of the above described lane departureprevention apparatus that has the departure preventing device, the lanedeparture prevention apparatus further comprises a lane keeping devicethat is configured to control the steering apparatus so that the vehicletravels within the driving lane, regardless of the possibility that thevehicle departs from the driving lane, the departure preventing deviceis configured to prevent the vehicle from departing from the drivinglane by controlling the steering apparatus and the braking apparatus,when it is determined that the departure condition and the abnormalitycondition are satisfied and the lane keeping device controls thesteering apparatus, the departure preventing device is configured toprevent the vehicle from departing from the driving lane by controllingthe braking apparatus, when it is determined that the departurecondition and the abnormality condition are satisfied and the lanekeeping device does not control the steering apparatus.

According to this aspect, when it is determined that the departurecondition and the abnormality condition are satisfied and the controlleror the lane keeping device controls the steering apparatus, thedeparture of the vehicle from the driving lane is prevented by using notonly the braking apparatus but also the steering apparatus that isalready controlled.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram that illustrates a structure of a vehicle in afirst embodiment.

FIG. 2 is a flowchart that illustrates a flow of an automatic evaluationoperation in the first embodiment.

FIG. 3 is a flowchart that illustrates a flow of a departure preventionoperation in the first embodiment.

FIG. 4 is a flowchart that illustrates a flow of a departure preventionoperation in a second embodiment.

FIG. 5 is a block diagram that illustrates a structure of a vehicle in athird embodiment.

FIG. 6 is a flowchart that illustrates a flow of a departure preventionoperation in the third embodiment.

DESCRIPTION OF EMBODIMENTS

In the following description, with reference to drawings, one embodimentof a lane departure prevention apparatus of the present invention willbe described. In the following description, a vehicle 1 to which oneembodiment of the lane departure prevention apparatus of the presentinvention is adapted will be described.

(1) First Embodiment (1-1) Structure of Vehicle 1

Firstly, with reference to a block diagram that is illustrated in FIG.1, the structure of the vehicle 1 of the first embodiment will beexplained. As illustrated in FIG. 1, the vehicle 1 has: a brake pedal111; a master cylinder 112; a brake pipe 113FL; a brake pipe 113RL; abrake pipe 113FR; a brake pipe 113RR; a left front wheel 121FL; a leftrear wheel 121RL; a right front wheel 121FR; a right rear wheel 121RR; awheel cylinder 122FL; a wheel cylinder 122RL; a wheel cylinder 122FR; awheel cylinder 122RR; a brake actuator 13 that is one specific exampleof the above described “braking apparatus”; a steering wheel 141, asteering actuator 142 that is one example of the above described“steering apparatus”; a vehicle speed sensor 151; a wheel speed sensor152; a yaw rate sensor 153; an acceleration sensor 154; an outer camera155; an inner camera 156; a display 161; and an ECU (Electronic ControlUnit) 17 that is one example of the above described “lane departureprevention apparatus”.

The brake pedal 111 is a pedal that is pedaled by a driver to brake thevehicle 1. The master cylinder 112 is configured to adjust pressure ofbrake fluid (alternatively, any fluid) in the master cylinder 112 sothat the pressure of the brake fluid is equal to pressure based on apedaled amount of the brake pedal 111. The pressure of the brake fluidin the master cylinder 112 is transmitted to the wheel cylinder 122FL,the wheel cylinder 122RL, the wheel cylinder 122FR and the wheelcylinder 122RR through the brake pipe 113FL, the brake pipe 113RL, thebrake pipe 113FR and the brake pipe 113RR, respectively. Thus, thebraking forces based on the pressure of the brake fluid transmitted tothe wheel cylinder 122FL, the wheel cylinder 122RL, the wheel cylinder122FR and the wheel cylinder 122RR are applied to the left front wheel121FL, the left rear wheel 121RL, the right front wheel 121FR and theright rear wheel 121RR, respectively.

The brake actuator 13 is configured to adjust the pressure of the brakefluid transmitted to each of the wheel cylinder 122FL, the wheelcylinder 122RL, the wheel cylinder 122FR and the wheel cylinder 122RRunder the control of the ECU 17, independently from the pedaled amountof the brake pedal 111. Therefore, the brake actuator 13 is configuredto adjust the braking force applied to each of the left front wheel121FL, the left rear wheel 121RL, the right front wheel 121FR and theright rear wheel 121RR, independently from the pedaled amount of thebrake pedal 111.

The steering wheel 141 is an operational device that is operated by thedriver to steer the vehicle 1 (namely, to turn turned wheels). Note thateach of the left front wheel 121FL and the right front wheel 121FRcorresponds to the turned wheel in the first embodiment.

The steering actuator 142 is configured to adjust a turned angle of theturned wheels under the control of the ECU 17, independently from theoperated amount of the steering wheel 141. Therefore, the steeringactuator 142 is configured to adjust a traveling direction (in otherwords, a turned direction) of the vehicle 1, independently from theoperated amount of the steering wheel 141. Namely, the steering actuator142 substantially constitutes an EPS (Electric Power Steering). Notethat the steering actuator 142 is configured to rotate the steeringwheel 141 that is coupled to the turned wheels simultaneously withturning the turned wheels.

The vehicle speed sensor 151 is configured to detect vehicle speed Vv ofthe vehicle 1. The wheel speed sensor 152 is configured to detect wheelspeed Vw of each of the left front wheel 121FL, the left rear wheel121RL, the right front wheel 121FR and the right rear wheel 121RR. Theyaw rate sensor 153 is configured to detect yaw rate γ of the vehicle 1.The acceleration sensor 154 is configured to detect acceleration G(specifically, acceleration Gx in a longitudinal direction (in otherwords, a front-back direction) and acceleration Gy in a lateraldirection (in other words, a right-left direction)) of the vehicle 1.The outer camera 155 is an imaging device that is configured to capturean outer circumstance in front of the vehicle 1. The inner camera 156 isan imaging device that is configured to capture a circumstance in avehicle interior of the vehicle 1 (especially, a circumstance of theperson in the vehicle 1). Detection data that represents the detectionresult of the vehicle speed sensor 151 to the acceleration sensor 154,outer image data that represents an outer image captured by the outercamera 155 and inner image data that represents an inner image capturedby the inner camera 156 are outputted to the ECU 17.

The display 161 is configured to display any information under thecontrol of the ECU 17.

The ECU 17 is configured to control entire operation of the vehicle 1.Especially in the first embodiment, the ECU 17 is configured to performan automatic evacuation operation for automatically evacuating(specifically, stopping) the vehicle 1 when it is difficult for theperson in the vehicle 1 to normally drive the vehicle 1. Therefore, theECU 17 is configured to function as a controlling apparatus forrealizing what we call deadman system. Moreover, in the firstembodiment, the ECU 17 is configured to perform a departure preventionoperation for preventing the vehicle 1 from departing (in other words,deviating) from a driving lane on which the vehicle 1 is currentlytraveling (in other words, moving). Therefore, the ECU 17 is configuredto function as a controlling apparatus for realizing what we call LDA(Lane Departure Alert) or LDP (Lane Departure Prevention).

In order to perform the automatic evacuation operation and the departureprevention operation, the ECU 17 includes, as processing blocks that arelogically realized in the ECU 17 or processing circuits that arephysically realized in the ECU 17, a data correcting unit 170, adeparture determining unit 171 that is one example of the abovedescribed “first determining device”, a LDA controlling unit 172 that isone specific example of the above described “departure preventingdevice”, an abnormality determining unit 173 that is one example of theabove described “second determining device” and an automatic evacuatingunit 174. Although an operation of each of the data correcting unit 170,the departure determining unit 171, the LDA controlling unit 172, theabnormality determining unit 173 and the automatic evacuating unit 174will be described later in detail with reference to FIG. 2 and so on,overview of the operation will be briefly described here. The datacorrecting unit 170 is configured to correct the detection data thatrepresents the detection result of the vehicle speed sensor 151 to theacceleration sensor 154, the outer image data that represents the outerimage captured by the outer camera 155 and the inner image data thatrepresents the inner image captured by the inner camera 156. Thedeparture determining unit 171 is configured to determine on the basisof the detection data and the outer image data corrected by the datacorrecting unit 170 whether or not a departure condition is satisfied.The departure condition is a condition that there is a possibility thatthe vehicle 1 departs from the driving lane on which the vehicle 1 iscurrently traveling. The LDA controlling unit 172 is configured toprevent the vehicle 1 from departing from the driving lane bycontrolling at least one of the steering actuator 142 and the brakeactuator 13 when the departure determining unit 171 determines that thedeparture condition is satisfied. Namely, the LDA controlling unit 172is configured to prevent the vehicle 1 from departing from the drivinglane by controlling at least one of the traveling direction of thevehicle 1 and the braking force applied to the vehicle 1. Note that“preventing the vehicle 1 from departing from the driving lane” in thefirst embodiment means allowing a distance by which the vehicle 1actually departs from the driving lane when at least one of thetraveling direction and the braking force is controlled to be smallerthan a distance by which the vehicle 1 is predicted to depart from thedriving lane when the traveling direction and the braking force are notcontrolled. The abnormality determining unit 173 is configured todetermine on the basis of the inner image data corrected by the datacorrecting unit 170 whether or not an abnormality condition issatisfied. The abnormality condition is a condition that it is difficultfor the person in the vehicle 1 to normally drive the vehicle 1. Theautomatic evacuating unit 174 is configured to automatically evacuatethe vehicle 1 to a desired evacuation place to which the vehicle 1 isallowed to evacuate safely by controlling at least one of the brakeactuator 13 and the steering actuator 142 when the abnormalitydetermining unit 173 determines that the abnormality condition issatisfied.

(1-2) Operation Performed by ECU in First Embodiment

Next, the automatic evacuation operation and the lane departureprevention operation that are performed by the ECU 17 will be describedin order. Note that it is preferable that the automatic evacuationoperation and the lane departure prevention operation are performed inparallel. However, the lane departure prevention operation may beperformed when the automatic evacuation operation is not performed.

(1-2-1) Flow of Automatic Evacuation Operation in First Embodiment

Firstly with reference to a flowchart illustrated in FIG. 2, a flow ofthe automatic evacuation operation will be described. As illustrated inFIG. 2, firstly, the data correcting unit 170 corrects the detectiondata that represents the detection result of the vehicle speed sensor151 to the acceleration sensor 154, the outer image data that representsthe outer image captured by the outer camera 155 and the inner imagedata that represents the inner image captured by the inner camera 156 (astep S101).

Then, the abnormality determining unit 173 determines on the basis ofthe inner image data corrected at the step S101 whether or not theabnormality condition that it is difficult for the person in the vehicle1 to normally drive the vehicle 1 is satisfied (a step S102). Theabnormality determining unit 173 may use, as an operation fordetermining whether or not the abnormality condition is satisfied, anexisting operation (for example, an operation described in the PatentLiterature 1). In the following description, one example of theoperation for determining whether or not the abnormality condition issatisfied will be described. For example, the abnormality determiningunit 173 may identify a direction of a face of the person in the vehicle1 by analyzing the image in the vehicle interior (especially, the imageof the person in the vehicle 1) represented by the inner image data, andthen, may determine that the abnormality condition is satisfied when astate where the person in the vehicle 1 does not face the front is keptfor over a first predetermined time. For example, the abnormalitydetermining unit 173 may identify an opening degree of eyes of theperson in the vehicle 1 by analyzing the image in the vehicle interior(especially, the image of the person in the vehicle 1) represented bythe inner image data, and then, may determine that the abnormalitycondition is satisfied when a state where the person in the vehicle 1closes his eyes is kept for over a second predetermined time. Note thateach of a situation where the person in the vehicle 1 dies suddenly anda situation where the person in the vehicle 1 loses his consciousness isone example of the situation where the abnormality condition issatisfied.

As a result of the determination at the step S102, if it is determinedthat the abnormality condition is not satisfied (the step S102: No), theECU 17 terminates the automatic evacuation operation illustrated in FIG.2. If the automatic evacuation operation illustrated in FIG. 2 isterminated, the ECU 17 may start the automatic evacuation operationillustrated in FIG. 2 again after a first restart period (for example,several milli seconds to several dozen milli second) has elapsed.Namely, the automatic evacuation operation illustrated in FIG. 2 isperformed periodically with the first restart period.

On the other hand, as a result of the determination at the step S102, ifit is determined that the abnormality condition is satisfied (the stepS102: Yes), the automatic evacuating unit 174 automatically evacuatesthe vehicle 1 to the desired evacuation place to which the vehicle 1 isallowed to evacuate safely by controlling at least one of the brakeactuator 13 and the steering actuator 142 (a step S103). The automaticevacuating unit 174 may use, as an operation for automaticallyevacuating the vehicle 1, an existing operation (for example, anoperation described in the Patent Literature 1). In the followingdescription, one example of the operation for automatically evacuatingthe vehicle 1 will be described. For example, the automatic evacuatingunit 174 may identify the desired evacuation place on the basis of theouter image data corrected at the step S101. Each of a side strip, aparking site and the like is one example of the desired evacuationplace. Then, the automatic evacuating unit 174 calculates a route fromthe current position of the vehicle 1 to the desired evacuating place.Then, the automatic evacuating unit 174 controls at least one of thebrake actuator 13 and the steering actuator 142 (moreover, a powersource such as an engine or a motor, if needed) so that the vehicle 1moves along the calculated route and stops at the desired evacuationplace. As a result, the vehicle 1 stops at the desired evacuation placewithout the operation of the person in the vehicle 1.

(1-2-2) Flow of Lane Departure Prevention Operation in First Embodiment

Next, with reference to a flowchart illustrated in FIG. 3, a flow of thelane departure prevention operation performed in the first embodimentwill be described. As illustrated in FIG. 3, firstly, the datacorrecting unit 170 corrects the detection data that represents thedetection result of the vehicle speed sensor 151 to the accelerationsensor 154 and the outer image data that represents the outer imagecaptured by the outer camera 155 (a step S111).

Then, the departure determining unit 171 determines whether or not thedeparture condition that there is a possibility that the vehicle 1departs from the driving lane on which the vehicle 1 currently travelingis satisfied (a step S112). The departure determining unit 171 may use,as an operation for determining whether or not the departure conditionis satisfied, an existing operation. In the following description, oneexample of the operation for determining whether or not the departurecondition is satisfied will be described. For example, the departuredetermining unit 171 may detect, in the outer image, a white line(alternatively, any lane edge) that zones the driving lane on which thevehicle 1 is currently traveling by analyzing the outer image datacorrected at the step S111. Moreover, the departure determining unit 171may estimate, on the basis of the detection date corrected at the stepS111, a traveling area at which the vehicle 1 will travel (in otherwords, move or pass through) before a third predetermined time (forexample, a time necessary for the vehicle 1 to travel by a distancecorresponding to a front watching distance) has elapsed from now. Then,the departure determining unit 171 may determine on the basis of thedetected white line and the estimated traveling area whether or not thevehicle 1 crosses over or is on the white line within the thirdpredetermine time. If it is determined that the vehicle 1 crosses overor is on the white line within the third predetermine time, thedeparture determining unit 171 may determine that the departurecondition is satisfied.

As a result of the determination at the step S112, if it is determinedthat the departure condition is not satisfied (the step S112: No), thelane departure prevention operation illustrated in FIG. 3 is terminated.If the lane departure prevention operation illustrated in FIG. 3 isterminated, the ECU 17 may start the lane departure prevention operationillustrated in FIG. 3 again after a second restart period (for example,several milli seconds to several dozen milli second) has elapsed.Namely, the lane departure prevention operation illustrated in FIG. 3 isperformed periodically with the second restart period.

On the other hand, as a result of the determination at the step S112, ifit is determined that the departure condition is satisfied (the stepS112: Yes), the LDA controlling unit 172 warns the driver that there isa possibility that the vehicle 1 departs from the driving lane (a stepS113). For example, the LDA controlling unit 172 may control the display161 to display the image for informing that there is a possibility thatthe vehicle 1 departs from the driving lane.

Moreover, if it is determined that the departure condition is satisfied,the abnormality determining unit 173 determines whether or not theabnormality condition is satisfied (a step S114). Note that the processat the step S114 is same as the above described process as the stepS102. Therefore, if the automatic evacuation operation is performed inparallel with the lane departure prevention operation, the determinationresult of the abnormality determining unit 173 in the automaticevacuation operation may be used in the lane departure preventionoperation, instead of performing the process at the step S114.

As a result of the determination at the step S114, if it is determinedthat the abnormality condition is not satisfied (the step S114: No), theLDA controlling unit 172 prevents the vehicle 1 from departing from thedriving lane by controlling at least one of the steering actuator 142and the brake actuator 13.

Specifically, the LDA controlling unit 172 selects, as a controlledtarget that is used to prevent the vehicle 1 from departing from thedriving lane, at least one of the steering actuator 142 and the brakeactuator 13 on the basis of a traveling state of the vehicle 1. In orderto select the controlled target, the LDA controlling unit 172 determineswhether or not the traveling state of the vehicle 1 is a brake prioritystate in which preventing the vehicle 1 from departing from the drivinglane by controlling the brake actuator 13 is prioritized more thanpreventing the vehicle 1 from departing from the driving lane bycontrolling the steering actuator 142 (a step S115). The brake prioritystate is a traveling state that is determined in advance for eachvehicle 1 on the basis of at least one of a characteristics of thevehicle 1, a degree of safety in preventing the vehicle 1 from departingfrom the driving lane by controlling the steering actuator 142, a degreeof safety in preventing the vehicle 1 from departing from the drivinglane by controlling the brake actuator 13 and the like. Note that thebrake priority state is one specific example of the above described“predetermined state”.

As a result of the determination at the step S115, if it is determinedthat the traveling state of the vehicle 1 is the brake priority state(the step S115: Yes), the LDA controlling unit 172 prevents the vehicle1 from departing from the driving lane by controlling the brake actuator13 (a step S116). Specifically, for example, if it is determined thatthere is a possibility that the vehicle 1 departs from the driving laneto get across the white line that is located at the right side withrespect to a traveling direction (in other words, a moving direction) ofthe vehicle 1, the vehicle 1 is preferably turned toward the left withrespect to the traveling direction of the vehicle 1 in order to preventthe vehicle 1 from departing from the driving lane. In this case, theLDA controlling unit 172 controls the brake actuator 13 so that thebraking force is applied to at least one of the left front wheel 121FLand the left rear wheel 121RL and the braking force is not applied toeach of the right front wheel 121FR and the right rear wheel 121RR orthe relatively small braking force is applied to at least one of theright front wheel 121FR and the right rear wheel 121RR and therelatively large braking force is applied to at least one of the leftfront wheel 121FL and the left rear wheel 121RL. On the other hand, ifit is determined that there is a possibility that the vehicle 1 departsfrom the driving lane to get across the white line that is located atthe left side with respect to the traveling direction of the vehicle 1,the LDA controlling unit 172 controls the brake actuator 13 so that thebraking force is applied to at least one of right front wheel 121FR andthe right rear wheel 121RR and the braking force is not applied to eachof the left front wheel 121FL and the left rear wheel 121RL or therelatively small braking force is applied to at least one of the leftfront wheel 121FL and the left rear wheel 121RL and the relatively largebraking force is applied to at least one of the right front wheel 121FRand the right rear wheel 121RR.

On the other hand, as a result of the determination at the step S115, ifit is determined that the traveling state of the vehicle 1 is not thebrake priority state (the step S115: No), the traveling state of thevehicle 1 is estimated to be a steering priority state at whichpreventing the vehicle 1 from departing from the driving lane bycontrolling the steering actuator 142 is prioritized more thanpreventing the vehicle 1 from departing from the driving lane bycontrolling the brake actuator 13. The steering priority state is also atraveling state that is determined in advance for each vehicle 1 on thebasis of at least one of the characteristics of the vehicle 1, thedegree of safety in preventing the vehicle 1 from departing from thedriving lane by controlling the steering actuator 142, the degree ofsafety in preventing the vehicle 1 from departing from the driving laneby controlling the brake actuator 13 and the like, as with the brakepriority state. In this case, the LDA controlling unit 172 prevents thevehicle 1 from departing from the driving lane by controlling thesteering actuator 142 (a step S117). Specifically, for example, if it isdetermined that there is a possibility that the vehicle 1 departs fromthe driving lane to get across the white line that is located at theright side with respect to the traveling direction of the vehicle 1, theLDA controlling unit 172 controls the steering actuator 142 to turn thevehicle 1 toward the left with respect to the traveling direction of thevehicle 1. On the other hand, if it is determined that there is apossibility that the vehicle 1 departs from the driving lane to getacross the white line that is located at the left side with respect tothe traveling direction of the vehicle 1, the LDA controlling unit 172controls the steering actuator 142 to turn the vehicle 1 toward theright with respect to the traveling direction of the vehicle 1.

On the other hand, as a result of the determination at the step S114, ifit is determined that the abnormality condition is satisfied (the stepS114: Yes), the LDA controlling unit 172 prevents the vehicle 1 fromdeparting from the driving lane by controlling the brake actuator 13(the step S116). Namely, if it is determined that the abnormalitycondition is satisfied, the brake actuator 13 is controlled to preventthe vehicle 1 from departing from the driving lane, regardless of thetraveling state of the vehicle 1 (namely, regardless of the travelingstate of the vehicle 1 being the brake priority state or the steeringpriority state).

As described above, according to the first embodiment, if theabnormality condition is not satisfied, the LDA controlling unit 172prevents the vehicle 1 from departing from the driving lane bycontrolling at least one of the brake actuator 13 and the steeringactuator 142 that is selected on the basis of the traveling state of thevehicle 1 as a usual case. On the other hand, if the abnormalitycondition is satisfied, the LDA controlling unit 172 prevents thevehicle 1 from departing from the driving lane by controlling the brakeactuator 13 as an exceptional case. Thus, the LDA controlling unit 172is capable of preventing the vehicle 1 from departing from the drivinglane, even if the person in the vehicle 1 loses the consciousness andfalls onto or leans against the steering wheel 141 and thus it isdetermined that the abnormality condition is satisfied. Specifically,when the person in the vehicle 1 loses the consciousness and falls ontoor leans against the steering wheel 141, there is a possibility that thesteering wheel 141 is substantially immovable (in other words, fixed) bythe unconscious person. As a result, there is a possibility that thesteering wheel 141 is not rotatable by the steering actuator 142 andthus the turned wheels that are coupled to the steering wheel 141 cannotbe turned. Thus, there is a possibility that the LDA controlling unit172 cannot prevent the vehicle 1 from departing from the driving lane bycontrolling the steering actuator 142 when the abnormality condition issatisfied. However, in the first embodiment, the LDA controlling unit172 prevents the vehicle 1 from departing from the driving lane bycontrolling the brake actuator 13 that is controllable even if thesteering wheel 141 is immovable. Therefore, the LDA controlling unit 172is capable of appropriately preventing the vehicle 1 from departing fromthe driving lane even in the situation where the person in the vehicle 1has any abnormality.

Moreover, a turned amount (especially, a turned amount per unit of time,same is true in the following description) of the vehicle 1 that isrealized by controlling the brake actuator 13 is generally larger than aturned amount of the vehicle 1 that is realized by controlling thesteering actuator 142. This is because the turned direction of thevehicle 1 is preferably changed relatively moderately in order tosuppress anxiety feeling of the person in the vehicle 1 that is causedby a sudden change of the turned direction, when the steering actuator142 is controlled to prevent the vehicle 1 from departing from thedriving lane. Thus, if the brake actuator 13 is controlled to preventthe vehicle 1 from departing from the driving lane in the situationwhere the abnormality condition is satisfied, it is possible torelatively quickly complete the prevention of the departure of thevehicle 1 from the driving lane in the situation where it is difficultfor the person in the vehicle 1 to normally drive the vehicle 1.Therefore, the vehicle 1 travels relatively more safely.

Note that an operational state of the LDA controlling unit 172 isswitchable (in other words, can be changed) between an ON state and anOFF state in response to a request from the person in the vehicle 1. TheON state is a state where the LDA controlling unit 172 is allowed tocontrol at least one of the brake actuator 13 and the steering actuator142 in order to prevent the vehicle 1 from departing from the drivinglane. The OFF state is a state where the LDA controlling unit 172 doesnot control both of the brake actuator 13 and the steering actuator 142in order to prevent the vehicle 1 from departing from the driving lane.Here, when the operational state of the LDA controlling unit 172 is theOFF state, the LDA controlling unit 172 does not usually control thebrake actuator 13 and the steering actuator 142 even if the departuredetermining unit 171 determines that the departure condition issatisfied. However, if the departure condition and the abnormalitycondition are satisfied in the situation where the operational state ofthe LDA controlling unit 172 is the OFF state, the LDA controlling unit172 may change the operational state of the LDA controlling unit 172itself from the OFF state to the ON state and then prevent the vehicle 1from departing from the driving lane by controlling the brake actuator13. As a result, it is possible to increase an opportunity that thedeparture of the vehicle 1 from the driving lane is prevented. Note thatthe LDA controlling unit 172 in the OFF state is configured to monitorthe determination result of each of the departure determining unit 171and the abnormality determining unit 173, if the vehicle 1 uses a methodof changing the operational state of the LDA controlling unit 172 to theON state when the departure condition and the abnormality condition aresatisfied in the situation where the operational state of the LDAcontrolling unit 172 is the OFF state.

Moreover, in the above described description, the LDA controlling unit172 prevents the vehicle 1 from departing from the driving lane bycontrolling the brake actuator 13 at the step S116 in FIG. 3. However,the LDA controlling unit 172 may prevent the vehicle 1 from departingfrom the driving lane by additionally controlling the steering actuator142 in addition to the brake actuator 13 at the step S116 in FIG. 3. TheLDA controlling unit 172 may additionally control the steering actuator142 in order to make up for a shortage of the turned amount of thevehicle 1 when only the brake actuator 13 cannot generate a desiredturned amount that is necessary to prevent the vehicle 1 from departingfrom the driving lane.

Similarly, in the above described description, the LDA controlling unit172 prevents the vehicle 1 from departing from the driving lane bycontrolling the steering actuator 142 at the step S117 in FIG. 3.However, the LDA controlling unit 172 may prevent the vehicle 1 fromdeparting from the driving lane by additionally controlling the brakeactuator 13 in addition to the steering actuator 142 at the step S117 inFIG. 3. The LDA controlling unit 172 may additionally control the brakeactuator 13 in order to make up for a shortage of the turned amount ofthe vehicle 1 when only the steering actuator 142 cannot generate adesired turned amount that is necessary to prevent the vehicle 1 fromdeparting from the driving lane.

Moreover, in the above described description, the abnormalitydetermining unit 173 determines on the basis of the image in the vehicleinterior (especially, the image of the person in the vehicle 1) whetheror not the abnormality condition is satisfied. However, the abnormalitydetermining unit 173 may determine whether or not the abnormalitycondition is satisfied by using another method. For example, theabnormality determining unit 173 may determine that the abnormalitycondition is satisfied when the person in the vehicle 1 does not operatethe brake pedal 111, the steering wheel 141 and a not-illustratedacceleration pedal for over a fourth predetermined time although thevehicle 1 travels.

As described above, the automatic evacuation operation and the lanedeparture prevention operation may be performed in parallel. In thiscase, there is a possibility that the process for automaticallyevacuating the vehicle 1 (namely, the process at the step S103 in FIG.2) and the process for preventing the vehicle 1 from departing from thedriving lane (namely, the process at the step S116 in FIG. 3) areperformed in parallel. However, the ECU 17 may intervene between both ofthe process for automatically evacuating the vehicle 1 and the processfor preventing the vehicle 1 from departing from the driving lane sothat one of the process for automatically evacuating the vehicle 1 andthe process for preventing the vehicle 1 from departing from the drivinglane is performed and the other one of the process for automaticallyevacuating the vehicle 1 and the process for preventing the vehicle 1from departing from the driving lane is not performed. For example, theECU 17 may intervene between both of the process for automaticallyevacuating the vehicle 1 and the process for preventing the vehicle 1from departing from the driving lane so that the LDA controlling unit172 performs the process for preventing the vehicle 1 from departingfrom the driving lane before the automatic evacuating unit 174 startsthe process for automatically evacuating the vehicle 1 and the LDAcontrolling unit 172 does not perform the process for preventing thevehicle 1 from departing from the driving lane after the automaticevacuating unit 174 starts the process for automatically evacuating thevehicle 1. In this case, the departure of the vehicle 1 from the drivinglane is prevented after the abnormality condition is satisfied andbefore the process for automatically evacuating the vehicle 1 starts.

(2) Second Embodiment

Next, a vehicle 2 in a second embodiment will be described. The vehicle2 in the second embodiment is different from the vehicle 1 in the firstembodiment in that one portion of the lane departure preventionoperation in the second embodiment is different from the lane departureprevention operation in the first embodiment. Therefore, with referenceto a flowchart illustrated in FIG. 4, the lane departure preventionoperation in the second embodiment will be described. Note that adetailed description of a process in the second embodiment that is sameas the process in the first embodiment will be omitted by assigning thesame step number.

As illustrated in FIG. 4, the above described processed from the stepS111 to the step S114 are performed also in the second embodiment.

As a result of the determination at the step S114, if it is determinedthat the abnormality condition is not satisfied (the step S114: No), theLDA controlling unit 172 determines whether or not the traveling stateof the vehicle 1 is the brake priority state (the step S115). As aresult of the determination at the step S115, if it is determined thatthe traveling state of the vehicle 1 is not the brake priority state(the step S115: No), the LDA controlling unit 172 prevents the vehicle 1from departing from the driving lane by controlling the steeringactuator 142 also in the second embodiment, as with the first embodiment(the step S117). On the other hand, as a result of the determination atthe step S115, if it is determined that the traveling state of thevehicle 1 is the brake priority state (the step S115: Yes), the LDAcontrolling unit 172 determines whether or not the brake actuator 13(alternatively, another component included in a brake controllingsystem) fails (a step S211).

On the other hand, as a result of the determination at the step S114, ifit is determined that the abnormality condition is satisfied (the stepS114: Yes), the LDA controlling unit 172 determines whether or not thebrake actuator 13 (alternatively, another component included in thebrake controlling system) fails (the step S211).

As a result of the determination at the step S211, if it is determinedthat the brake actuator 13 does not fail (the step S211: No), the LDAcontrolling unit 172 prevents the vehicle 1 from departing from thedriving lane by controlling the brake actuator 13 (the step S116). Onthe other hand, as a result of the determination at the step S211, if itis determined that the brake actuator 13 fails (the step S211: Yes), theLDA controlling unit 172 prevents the vehicle 1 from departing from thedriving lane by controlling the steering actuator 142 instead ofcontrolling the failed brake actuator 13 (the step S117).

The above described lane departure prevention operation in the secondembodiment achieves the effect that is same as the effect achieved bythe lane departure prevention operation in the first embodiment.Moreover, in the second embodiment, the LDA controlling unit 172prevents the vehicle 1 from departing from the driving lane bycontrolling the steering actuator 142 instead of controlling the failedbrake actuator 13, if the brake actuator 13 that is the controlledtarget used to prevent the vehicle 1 from departing from the drivinglane fails. Thus, the departure of the vehicle 1 from the driving laneis appropriately prevented even if the brake actuator 13 fails.

Note that the LDA controlling unit 172 may determine whether or not thesteering actuator 142 (alternatively, another component included in asteering controlling system) fails before starting to control thesteering actuator 142 to prevent the vehicle 1 from departing from thedriving lane (namely, before performing the step S117). If it isdetermined that the steering actuator 142 does not fail, the LDAcontrolling unit 172 may prevent the vehicle 1 from departing from thedriving lane by controlling the steering actuator 142. On the otherhand, if it is determined that the steering actuator 142 fails, the LDAcontrolling unit 172 may prevent the vehicle 1 from departing from thedriving lane by controlling the brake actuator 13 instead of controllingthe failed steering actuator 142.

(3) Third Embodiment

Next, a vehicle 3 in a third embodiment will be described. The vehicle 3in the third embodiment is different from the vehicle 1 in the firstembodiment in that one portion of the structure of the vehicle 3 isdifferent from the structure of the vehicle 1 and one portion of thelane departure prevention operation in the third embodiment is differentfrom the lane departure prevention operation in the first embodiment.Therefore, with reference to FIG. 5 and FIG. 6, the structure of thevehicle 3 in the third embodiment and the lane departure prevention inthe third embodiment will be described. Note that a detailed descriptionof a component of the vehicle 3 that is same as the component of thevehicle 1 in the first embodiment will be omitted by assigning the samereference sign. Note that a detailed description of a process in thethird embodiment that is same as the process in the first embodimentwill be omitted by assigning the same step number.

(3-1) Structure of Vehicle 3 in Third Embodiment

With referent to a block diagram in FIG. 5, the structure of the vehicle3 in the third embodiment will be described. As illustrated in FIG. 5,the vehicle 3 is different from the vehicle 1 in that the vehicle 3 hasan ECU 37 instead of the ECU 17. The ECU 37 is different from the ECU 17in that the ECU 37 has a LKA (Lane Keep Assist) controlling unit 375that is one specific example of the above described “lane keepingdevice”.

The LKA controlling unit 375 is configured to control the steeringactuator 142 so that the vehicle 3 travels within (in other words,along) the driving lane on which the vehicle 3 is currently traveling.Note that the LKA controlling unit 375 and the LDA controlling unit 172have a common characteristics in that each of the LKA controlling unit375 and the LDA controlling unit 172 is allowed to prevent the vehicle 1from departing from the driving lane. However, the LKA controlling unit375 is different from the LDA controlling unit 172 in that the LKAcontrolling unit 375 controls the steering actuator 142 so that thevehicle 3 travels within the driving lane regardless of the satisfactionof the departure condition and the LDA controlling unit 172 controls atleast one of the steering actuator 142 and the brake actuator 13 toprevent the vehicle 3 from departing from the driving lane when thedeparture condition is satisfied.

(3-2) Flow of Lane Departure Prevention Operation in Third Embodiment

Next, with reference to a flowchart illustrated in FIG. 6, a flow of thelane departure prevention operation in the third embodiment will bedescribed. As illustrated in FIG. 6, the above described processed fromthe step S111 to the step S114 are performed also in the thirdembodiment.

As a result of the determination at the step S114, if it is determinedthat the abnormality condition is not satisfied (the step S114: No), theLDA controlling unit 172 determines whether or not the traveling stateof the vehicle 1 is the brake priority state (the step S115). As aresult of the determination at the step S115, if it is determined thatthe traveling state of the vehicle 1 is not the brake priority state(the step S115: No), the LDA controlling unit 172 prevents the vehicle 1from departing from the driving lane by controlling the steeringactuator 142 also in the third embodiment, as with the first embodiment(the step S117). On the other hand, as a result of the determination atthe step S115, if it is determined that the traveling state of thevehicle 1 is the brake priority state (the step S115: Yes), the LDAcontrolling unit 172 determines whether or not the LKA controlling unit375 controls the steering actuator 142 so that the vehicle 3 travelswithin the driving lane on which the vehicle 3 is currently travels (astep S311). Namely, the LDA controlling unit 172 determines whether ornot the LKA controlling unit 375 is working (the step S311).

On the other hand, as a result of the determination at the step S114, ifit is determined that the abnormality condition is satisfied (the stepS114: Yes), the LDA controlling unit 172 determines whether or not theLKA controlling unit 375 is working (the step S311).

As a result of the determination at the step S311, if it is determinedthat the LKA controlling unit 375 is not working (the step S311: No),the LDA controlling unit 172 prevents the vehicle 1 from departing fromthe driving lane by controlling the brake actuator 13 (the step S116).On the other hand, as a result of the determination at the step S311, ifit is determined that the LKA controlling unit 375 is working (the stepS311: Yes), the LDA controlling unit 172 prevents the vehicle 1 fromdeparting from the driving lane by controlling, in addition to the brakeactuator 13, the steering actuator 142 that is already working under thecontrol of the LKA controlling unit 375 (the step S312). Note that theLKA controlling unit 375 does not control the steering actuator 142after the LDA controlling unit 172 starts to control the steeringactuator 142. Namely, the control by the LDA controlling unit 172 isprioritized more than the control by the LKA controlling unit 375.

The above described lane departure prevention operation in the thirdembodiment achieves the effect that is same as the effect achieved bythe lane departure prevention operation in the first embodiment.Moreover, in the third embodiment, if it is determined that theabnormality condition is satisfied in the situation where the steeringactuator 142 is already working under the control of the LKA controllingunit 375, the departure of the vehicle 3 from the driving lane isprevented by allowing the steering actuator 142 that is already workingto keep working in addition to controlling the brake actuator 13. Thus,the LDA controlling unit 172 is allowed to prevent the vehicle 3 fromdeparting from the driving lane by controlling both of the brakeactuator 13 and the steering actuator 142 without newly allowing thesteering actuator 13 to newly start working. Moreover, the LDAcontrolling unit 172 is allowed to prevent the vehicle 3 from departingfrom the driving lane without causing the shortage of the turned amountof the vehicle 1 that is necessary to prevent the vehicle 1 fromdeparting from the driving lane, because the LDA controlling 172 isallowed to control both of the brake actuator 13 and the steeringactuator 142. In addition, the steering actuator 142 that is alreadyworking before the LDA controlling unit 172 starts to control the brakeactuator 13 in order to prevent the vehicle 3 from departing from thedriving lane keeps working in order to prevent the vehicle 3 fromdeparting from the driving lane. Thus, behavior of the vehicle 3 doesnot suddenly change due to the termination of the control of thesteering actuator 142, compared to the case where the control of thesteering actuator 142 is terminated after starting the control of thebrake actuator 13 to prevent the vehicle 3 from departing from thedriving lane.

At least one portion of the feature in the above described first tothird embodiments may be eliminated or modified accordingly. At leastone portion of the feature in the above described first to thirdembodiments may be combined with at least another one portion of thefeature in the above described first to third embodiments. At least oneportion of the feature in one of the above described first to thirdembodiments may be combined with at least another one portion of thefeature in another one of the above described first to thirdembodiments.

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2017-026725, filed on Feb. 16,2017, the entire contents of which are incorporated herein by reference.In addition, the entire contents of the above described PatentLiterature 1 is incorporated herein by reference.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although the embodiments of the presentinvention have been described in detail, it should be understood thatthe various changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention. A lanedeparture prevention apparatus, which involve such changes, are alsointended to be within the technical scope of the present invention.

REFERENCE SIGNS LIST

-   1, 2, 3 vehicle-   111 brake pedal-   112 master cylinder-   113FL, 113RL, 113FR, 113RR brake pipe-   121FL left front wheel-   121RL left rear wheel-   121FR right front wheel-   121RR right rear wheel-   122FL, 122RL, 122FR, 122RR wheel cylinder-   13 brake actuator-   141 steering wheel-   142 steering actuator-   151 vehicle speed sensor-   152 wheel speed sensor-   153 yaw rata sensor-   154 acceleration sensor-   155 outer camera-   156 inner camera-   161 display-   ECU (Electronic Control Unit)-   170 data correcting unit-   171 departure determining unit-   172 LDA controlling unit-   173 abnormality determining unit-   174 automatic evacuating unit-   375 LKA controlling unit-   Vv vehicle speed-   Vw wheel speed-   γ yaw rate-   G, Gx, Gy acceleration

1. A lane departure prevention apparatus comprising: an electroniccontrol unit (ECU), including a processor, programmed to: determinewhether or not a departure condition is satisfied, the departurecondition being a condition that there is a possibility that a vehicledeparts from a driving lane on which the vehicle is currently traveling;determine whether or not a predetermined abnormality condition issatisfied, the abnormality condition is a condition that it is difficultfor a person in the vehicle to normally drive the vehicle; based upon adetermination that the departure condition and the abnormality conditionare satisfied, determine whether or not a braking actuator is failing;based upon a determination that the braking actuator is not failing,perform a lane departure prevention operation by preventing the vehiclefrom departing from the driving lane by controlling the brakingactuator; and based upon a determination that the braking actuator isfailing, perform the lane departure prevention operation by preventingthe vehicle from departing from the driving lane by controlling thesteering actuator without controlling the braking apparatus.
 2. The lanedeparture prevention apparatus according to claim 1, wherein, based uponthe determination that the departure condition is satisfied, the ECU isfurther programmed to inform a driver of the departure condition toindicate a possibility that vehicle will depart from the driving lane.3. The lane departure prevention apparatus according to claim 1, furthercomprising an inner camera configured to capture image data thatrepresents an inner image in a vehicle interior of the vehicle includinga driver, wherein the determination of whether the abnormality conditionexists is based on the inner image data.
 4. The lane departureprevention apparatus according to claim 3, wherein the ECU is furtherprogrammed to perform an automatic evacuation operation after the lanedeparture prevention operation is performed, wherein the ECU isprogrammed to: calculate a route from a current position of the vehicleto an evacuation position, control at least one of the brake actuatorand the steering actuator so that the vehicle moves along the calculatedroute, and stop the vehicle at the evacuation position.